Top Dog, a new book by Po Bronson and Ashley Merryman about “the science of winning and losing” is in large part a celebration of competition. The authors of the bestselling NurtureShock explore the benefits of what they call “competitive fire” — stories of Olympic swimmers, champion chess players, and upstart political candidates who reached the top by racing someone else. But just as interesting are the cases in which we do better without the element of competition. Sometimes, it turns out, competing against others can actually make our performance worse.

Bronson and Merryman describe an experiment in which researchers gave 124 Princeton University underclassmen a test that drew its questions from the GRE, the graduate school admissions test. For some of the students, the investigators added to the stress of this difficult exam in two ways. First, the students were asked to report which high school they’d attended and how many of their high school classmates were also at Princeton. “This was intended to make most test-takers feel as if they were alone at Princeton, that they were lucky to be at Princeton, and that they had barely made the bar for admittance,” Bronson and Merryman explain.

Second, researchers further added to students’ stress by labeling the test as an “Intellectual Ability Questionnaire.” Bronson and Merryman again: “They wanted the test’s title to be threatening to the students, to make the students fear that, if they did poorly, the test would reveal they lacked the true ability to be at Princeton.” The other group of students answered the questions about high school only after taking the test, when it could no longer affect their performance, and their exam went by the less-threatening name “Intellectual Challenge Questionnaire.”

The results? Students in the first group answered 72% of the questions correctly; those in the second group got 90% of their answers right. By subtly manipulating the competitive stress felt by the participants, Bronson and Merryman note, the researchers “were able to engineer an 18% difference in their test scores.”

The research literature is full of such findings. Take a classic study of the phenomenon known as “stereotype threat,” the apprehension felt by members of certain groups, such as female or African-American students, that a poor performance will confirm a negative stereotype about them–“girls aren’t good at math” or “blacks aren’t college material”. Published in the Journal of Personality and Social Psychology in 1995, the study had groups of students, both white and black, take the same test; as in the Princeton experiment described by Bronson and Merryman, the test was presented slightly differently to each group. Some participants were told that that the test would evaluate their intellectual abilities; others were told that it was a laboratory puzzle task that did not assess ability.

Black students who thought their intelligence was being evaluated did worse on the test than their white counterparts, while black students who believed they were simply figuring out puzzles (a condition the researchers termed “stereotype-safe”) did much better, equaling the white students’ scores. A follow-up study found that self-doubts and negative racial stereotypes were more likely to intrude on the thoughts of African-American students who anticipated taking an evaluative test; African-American students who expected to complete a puzzle exercise were less likely to encounter such thoughts.

So when does competition help our performance, and when does it hurt? One more story from Bronson and Merryman helps make the distinction clear. In the mid-1990s, they recount, the commandant of the U.S. Air Force Academy became concerned that the number of cadets experiencing academic trouble was on the rise. Economists Scott Carrell and James West studied the cadets and noticed a pattern: cadets with lower grades improved academically if they spent time with cadet friends who did well in school. So the academy deliberately engineered the composition of the squadrons of entering cadets, grouping cadets with lower GPAs and SAT scores with cadets who’d achieved high grades and scores.

The intervention was a failure. The low-performing cadets actually did worse than before. Why? Unable to compete with their high-flying squadron mates, the low-performers gave up trying. Bronson and Merryman deliver the takeaway: “Contests only work when it’s an even match up, or a close race, such that the extra effort becomes the decider between wining and losing. People need at least a fighting chance. When leaders are not challenged, they coast a little. Those too far behind stop trying as hard, lacking any sense that winning is feasible.”

Human beings are supremely sensitive to context, to the cues we sense in our surroundings, and never more so than when we’re performing. When you feel stressed or threatened, you can try mentally reframing the situation as a game or a challenge; when young people feel anxious, parents and teachers can help by downplaying the evaluative nature of the event.But when we feel strong and capable, when we feel like a contender — then we can use the spur of competition to reach new heights.